With the broad goal of understanding principles common to processing sensory information in various modalities, this research aims to understand the role of voluntary attention in perception, particularly in the detection of weak sensory stimuli. In detecting auditory stimuli, people can attend selectively to information processed in different subpopulations of peripheral neural inputs (auditory listening-bands or attention-bands). A similar principle may operate in other modalities, such as touch and taste. Thus, selective attention may tap people's ability to monitor selectively a single channel (class of fibers) for the presence of neural information, e.g., Pacinian-based versus rapidly-adapting fibers in touch. (1) Experiments will use criterion-controlled psychophysical methods to test the hypothesis that channels analogous to auditory listening-bands also underlie the detection of weak tactile and gustatory stimuli. It is possible, however, that people can also attend selectively to stimuli that produce different patterns of neural activity within a single channel. Experiments will test this hypothesis directly. (2) In touch, spatial attention-the ability to attend to different parts of the body surface-appears to depend on inputs from proprioception (orientation of the head and eyes) and possibly vision; and in hearing, spatial attention may depend on visual inputs. Experiments will test the hypotheses that tactile spatial attention is linked to proprioception and that auditory spatial attention is linked to vision. (3) People can attend selectively to sounds having particular durations. The ability to attend selectively to sensory events having a particular duration could be a general property of perceptual systems. Experiments will test the hypothesis that temporal attention is a property of touch as well as hearing. (4) There is evidence for the existence in the Pacinian tactile system of energy thresholds, levels below which stimulation is indistinguishable from the absence of stimulation. Experiments will test two hypotheses: first, that energy thresholds are established subsequent to temporal and spatial summation in the Pacinian system, and second, that attention can operate by modulating these central energy thresholds. Taken together, these studies will elucidate basic mechanisms governing the role of attention in perception, and by doing so may ultimately help to advance our understanding of such disturbances of attention as those associated with communicative disorders, with brain injury and stroke, and with childhood learning disorders.